JP2017123265A - Ion source and insulating mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance reliability of an ion source.SOLUTION: An ion source 10 includes a plasma chamber 12 to which high potential is applied, an insulating mechanism 50 provided so as to surround the outer periphery of the plasma chamber 12, a magnetic field generator 16 which is provided outside the insulating mechanism 50 and generates magnetic field in the plasma chamber 12, and a vacuum chamber 18 for housing the plasma chamber 12, the insulating mechanism 50 and the magnetic field generator 16 therein. The insulating mechanism 50 has plural conductor layers (an inner conductor layer 54, an intermediate conductor layer 55, an outer conductor layer 56) and plural insulation layers 52a which are alternately stacked in a direction from the plasma chamber 12 to the magnetic field generator 16.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ion source having an insulating mechanism.

  There is known an ion source configured to generate a magnetic field in a plasma chamber by a magnetic field generator provided on the outer periphery of the plasma chamber to generate plasma in the plasma chamber, and to extract ions from the plasma chamber using an extraction electrode. The ions extracted from the ion source are used, for example, for an ion implantation process. In order to efficiently extract ions from the plasma chamber, a power source for applying a high voltage is connected to the plasma chamber.

JP2015-109150A

  Since the ion source is used by being incorporated into an apparatus or the like for ion implantation processing, the apparatus is required to be small in consideration of restrictions such as space. On the other hand, when trying to reduce the size of the apparatus, it may be difficult to ensure insulation between the plasma chamber to which a high voltage is applied and its surroundings.

  One exemplary objective of certain aspects of the present invention is to increase the reliability of the ion source.

  An ion source according to an aspect of the present invention includes a plasma chamber to which a high potential is applied, an insulating mechanism provided so as to surround an outer periphery of the plasma chamber, and a magnetic field that is provided outside the insulating mechanism and generates a magnetic field in the plasma chamber. A generator, and a vacuum chamber that houses the plasma chamber, the insulating mechanism, and the magnetic field generator. The insulation mechanism has a plurality of conductor layers and a plurality of insulation layers alternately stacked in a direction from the plasma chamber toward the magnetic field generator.

  Another aspect of the present invention is an insulating mechanism for electrically insulating the first member and the second member. In this insulation mechanism, a laminated region in which a plurality of conductor layers and a plurality of insulating layers are alternately laminated in a direction from the first member to the second member, and an end insulator covering the ends of the plurality of conductor layers are provided. An end region to be provided.

  Note that any combination of the above-described constituent elements and the constituent elements and expressions of the present invention replaced with each other among methods, apparatuses, systems, and the like are also effective as an aspect of the present invention.

  According to the present invention, the reliability of the ion source can be improved.

It is a figure which shows typically the structure of the ion source which concerns on embodiment. It is sectional drawing which shows typically the structure of the ion source which concerns on embodiment. It is a figure which shows typically the electric field and magnetic field which arise between a plasma chamber and a magnetic field generator in the ion source which concerns on a comparative example. It is a figure which shows typically the structure of the insulation mechanism which concerns on a comparative example. It is a figure which shows typically the structure of the insulation mechanism which concerns on embodiment. It is a figure which shows typically the structure of the insulation mechanism which concerns on a modification. It is a figure which shows typically the structure of the insulation mechanism which concerns on a modification. It is a figure which shows typically the structure of the insulation mechanism which concerns on a modification.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description, the same elements are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate.

  1 and 2 schematically show a configuration of an ion source 10 according to the embodiment, and FIG. 2 shows a cross section taken along line AA in FIG. The ion source 10 inputs a microwave power C to a plasma chamber 12 to which a magnetic field satisfying an electron cyclotron resonance (ECR) condition or a magnetic field higher than that is applied, and generates a high-density plasma to extract ions. It is. The ion source 10 is configured to generate a plasma of a source gas by the interaction between a magnetic field and a microwave, and to extract ions from the plasma to the outside of the plasma chamber 12.

  The ion source 10 is used as an ion source for an ion implantation apparatus or a particle beam therapy apparatus, for example. The ion source 10 is used as a monovalent ion source, for example. The ion source 10 can also be used as an ion source for a proton accelerator or an X-ray source.

  As is well known, the strength of the magnetic field that satisfies the ECR condition is uniquely determined with respect to the microwave frequency used, and a magnetic field of 87.5 mT (875 gauss) is required when the microwave frequency is 2.45 GHz. It is. Hereinafter, for convenience of explanation, a magnetic field that satisfies the ECR condition may be referred to as a resonance magnetic field.

  The ion source 10 includes a plasma chamber 12, a magnetic field generator 16, and a vacuum vessel 18. The plasma chamber 12 and the magnetic field generator 16 are accommodated in the vacuum vessel 18. The plasma chamber 12 is a vacuum chamber configured to generate and maintain plasma in its internal space. Hereinafter, the internal space of the plasma chamber 12 may be referred to as a plasma generation space 14.

  The plasma chamber 12 has a cylindrical shape having both ends. Hereinafter, the direction from one end to the other end of the plasma chamber 12 may be referred to as an axial direction for convenience. In addition, a direction orthogonal to the axial direction may be referred to as a radial direction, and a direction surrounding the axial direction may be referred to as a circumferential direction. However, these do not necessarily mean that the plasma chamber 12 has a rotationally symmetric shape. The axial length of the plasma chamber 12 may be longer or shorter than the radial length of the end portion of the plasma chamber 12.

  The plasma chamber 12 includes an ion extraction unit 22 and a microwave introduction unit 26. The ion extraction unit 22 and the microwave introduction unit 26 are opposed to each other with the plasma generation space 14 interposed therebetween. The plasma chamber 12 includes a side wall portion 20 that connects the ion extraction portion 22 and the microwave introduction portion 26 and surrounds the plasma generation space 14. The side wall part 20 is fixed to the outer peripheral part of each of the ion extraction part 22 and the microwave introduction part 26. The side wall portion 20 is formed of a nonmagnetic metal material such as stainless steel or aluminum.

  Note that the side wall 20 may include a cooling unit for cooling the side wall 20. This cooling part may be built in the side wall part 20 or may be attached outside the side wall part 20. Moreover, in order to protect the side wall part 20 of the plasma chamber 12 from a plasma, the liner (for example, boron nitride) which coat | covers the inner surface of the side wall part 20 may be provided.

  A plasma generation space 14 is defined in the plasma chamber 12 by the microwave introduction part 26, the ion extraction part 22, and the side wall part 20. The plasma chamber 12 is configured such that the microwave introduction part 26, the ion extraction part 22, and the side wall part 20 integrally surround the plasma generation space 14, so that the side wall part 20 connected to the ion extraction part 22 is provided. The end can also be regarded as a part of the ion extraction part 22. Similarly, the end of the side wall part 20 connected to the microwave introduction part 26 can also be regarded as a part of the microwave introduction part 26.

  The plasma chamber 12 has, for example, a cylindrical shape. In this case, the microwave introduction part 26 and the ion extraction part 22 are substantially disk-shaped, and the side wall part 20 is substantially cylindrical. The plasma chamber 12 may have any shape as long as plasma can be appropriately accommodated.

  The microwave introduction unit 26 includes a vacuum window 32. The vacuum window 32 seals the inside of the plasma chamber 12 to a vacuum. One side of the vacuum window 32 faces the plasma generation space 14, and the other side of the vacuum window 32 is directed to the microwave supply system or the waveguide 30. The propagation direction C of the microwave is perpendicular to the vacuum window 32. In the present embodiment, the vacuum window 32 occupies the entire microwave introduction part 26, but the vacuum window 32 may be formed in a part (for example, the central part) of the microwave introduction part 26.

  The microwave incident power to the plasma chamber 12 is greater than about 100 W, for example. Alternatively, the microwave incident power to the plasma chamber 12 may be about 500 W or more, or about 1 kW or more. The waveguide 30 and the vacuum window 32 are suitable for supplying such a high-power microwave compared to other supply means such as a coaxial line.

The vacuum window 32 is made of a dielectric such as alumina (Al ₂ O ₃ ) or boron nitride (BN). The vacuum window 32 may have a two-layer structure including an alumina layer and a boron nitride layer. For example, a boron nitride layer is provided on the surface of the vacuum window 32 made of alumina in contact with the plasma generation space 14. Thereby, the boron nitride layer covering the vacuum window 32 protects the vacuum window 32 from electrons flowing back from the outside of the plasma chamber 12 to the plasma chamber 12 through the extraction opening 24.

  On the other hand, at least one extraction opening 24 is formed in the ion extraction portion 22. The drawer opening 24 is, for example, a slit that is elongated in a direction perpendicular to the paper surface. The extraction opening 24 is formed in the central portion of the ion extraction portion 22. The extraction opening 24 is formed at a position facing the vacuum window 32 across the plasma generation space 14. The vacuum window 32, the plasma generation space 14, and the extraction opening 24 are arranged along the central axis of the plasma chamber 12.

  The plasma chamber 12 is connected to a power source 62 for applying a positive high voltage. When a high voltage is applied to the plasma chamber 12, the same high voltage is also applied to the ion extraction part 22, which is a part of the plasma chamber 12. Therefore, the ion extraction part 22 may be called a plasma electrode.

  An extraction electrode system having at least one extraction electrode 40 for extracting ions to the outside of the plasma chamber 12 is provided outside the extraction opening 24 in the axial direction. The extraction electrode 40 is opposed to the ion extraction portion 22 with an extraction gap 42 in the axial direction. The extraction electrode 40 is formed, for example, in an annular shape, and has an opening 44 for allowing ions extracted from the plasma chamber 12 to pass through at the center thereof. In addition, the extraction electrode system includes an extraction power source (not shown) for applying a potential to the extraction electrode 40.

  The magnetic field generator 16 is disposed so as to surround the side wall portion 20 of the plasma chamber 12 in order to generate a magnetic field directed in the axial direction on the central axis of the plasma chamber 12. The direction of the line of magnetic force is indicated by an arrow B in FIG. The magnetic field line direction B by the magnetic field generator 16 is the same direction as the microwave propagation direction C. Further, the magnetic field B has a resonance magnetic field or higher intensity at least at a part on the central axis of the plasma chamber 12. The magnetic field generator 16 can also generate a magnetic field lower than the resonance magnetic field in at least a part of the axis of the plasma chamber 12.

  The magnetic field generator 16 has an annular coil, and a conducting wire is wound around the plasma chamber 12 in the circumferential direction. The magnetic field generator 16 has a coil power supply (not shown) for flowing a current through the coil. A plurality of the magnetic field generators 16 may be arranged along the axial direction of the plasma chamber 12 and may include a permanent magnet instead of the coil.

  The magnetic field generator 16 is directly attached to the inner wall of the vacuum vessel 18 and grounded, for example. Therefore, different potentials are applied to the grounded magnetic field generator 16 and the plasma chamber 12 connected to the power source 62. In the present embodiment, an insulating mechanism 50 is provided in a region between the plasma chamber 12 and the magnetic field generator 16 in order to enhance insulation between the plasma chamber 12 and the magnetic field generator 16 having different potentials.

  The insulating mechanism 50 includes an insulating member 52, an inner conductor layer 54, a plurality of intermediate conductor layers 55, and an outer conductor layer 56. The insulating member 52 includes a plurality of insulating layers 52a, a first end insulator 52c, and a second end insulator 52d. The insulating mechanism 50 has a laminated structure in which a plurality of conductor layers (inner conductor layer 54, intermediate conductor layer 55, outer conductor layer 56) and a plurality of insulating layers 52a are alternately laminated in the radial direction.

  The insulating mechanism 50 is provided so as to surround the outer periphery of the side wall portion 20. The insulating mechanism 50 is provided away from the side wall 20 in the radial direction, and has a cylindrical shape corresponding to the cylindrical plasma chamber 12. The insulating mechanism 50 is also provided away from the magnetic field generator 16 in the radial direction. The insulating mechanism 50 is supported by a flange portion 28 provided in the microwave introduction portion 26. The insulating mechanism 50 may be fixed to the outer periphery of the plasma chamber 12 by a fixing member (not shown).

  The inner conductor layer 54 is provided inside the insulating member 52 and constitutes the inner side surface 50 a of the insulating mechanism 50. The inner conductor layer 54 avoids the first end 50 c located near the extraction electrode 40 and the second end 50 d located near the flange portion 28 of the microwave introduction portion 26 in order to prevent creeping discharge. Provided. That is, the inner conductor layer 54 is provided in the stacked region W1 that avoids the end region W2 of the insulating mechanism 50. In addition, the lamination | stacking area | region W1 means the range of the axial direction where the inner side conductor layer 54 and the outer side conductor layer 56 are laminated | stacked.

  The inner conductor layer 54 is preferably made of a material having high conductivity and heat conductivity, and is made of a nonmagnetic metal material such as copper (Cu) or aluminum (Al). The inner conductor layer 54 is electrically connected to the plasma chamber 12 by the microwave introduction part 26, a fixing member (not shown), or the like. Therefore, the inner conductor layer 54 has the same potential as the plasma chamber 12 to which a high voltage is applied. The inner conductor layer 54 eliminates a potential difference between the inner surface 50 a of the insulating mechanism 50 and the plasma chamber 12, and prevents an electric field from being generated between the plasma chamber 12 and the insulating mechanism 50.

  The outer conductor layer 56 is provided outside the insulating member 52 and constitutes an outer surface 50 b of the insulating mechanism 50. The outer conductor layer 56 is preferably made of a material having high conductivity and heat conductivity, and is made of a nonmagnetic metal material such as copper or aluminum. The outer conductor layer 56 may be formed by coating a material having a small secondary electron emission coefficient such as titanium nitride (TiN). The outer conductor layer 56 is grounded and has the same potential as the magnetic field generator 16 and the vacuum vessel 18. The outer conductor layer 56 is provided at least at a position facing the magnetic field generator 16, and is provided to avoid the vicinity of the first end 50c and the second end 50d in order to prevent creeping discharge. Therefore, the outer conductor layer 56 is provided in the stacked region W1 avoiding the end region W2 of the insulating mechanism 50.

  The plurality of intermediate conductor layers 55 are cylindrical members provided between the inner conductor layer 54 and the outer conductor layer 56, and are disposed between the adjacent insulating layers 52a. The intermediate conductor layer 55 is preferably made of a material having high conductivity and heat conductivity, and is made of a nonmagnetic metal material such as copper or aluminum. The intermediate conductor layer 55 is formed so as to extend longer in the axial direction than the inner conductor layer 54 and the outer conductor layer 56, and the end portions 50 c and 50 c of the insulating mechanism 50 are formed more than the inner conductor layer 54 and the outer conductor layer 56. Extends close to 50d. That is, the intermediate conductor layer 55 extends so as to protrude in the axial direction from the stacked region W1 toward the end region W2.

  The insulating member 52 is formed of an insulating and heat-resistant material, and for example, a ceramic material such as alumina or a resin material such as polyimide is used. Note that the insulating mechanism 50 can be reduced in weight by using a resin material as the insulating member 52, and a cylindrical laminated structure can be easily formed.

  The plurality of insulating layers 52a are cylindrical members provided between the plurality of conductor layers, and electrically insulate between adjacent conductor layers. The first end insulator 52 c is provided at the first end 50 c of the insulating mechanism 50, and the second end insulator 52 d is provided at the second end 50 d of the insulating mechanism 50. The first end insulator 52c and the second end insulator 52d cover the end portion of the intermediate conductor layer 55 to prevent the occurrence of creeping discharge at the first end portion 50c and the second end portion 50d.

  The insulating mechanism 50 can be formed, for example, by laminating sheet-like metal materials and sheet-like resin materials alternately and thermocompression bonding. At this time, the resin layer may be formed such that a large number of resin sheets are sandwiched between two metal sheets so that the insulating layer 52a is relatively thicker than the intermediate conductor layer 55. Therefore, each insulating layer 52a may be composed of a plurality of resin sheets. Further, the layers constituting the insulating mechanism 50 do not necessarily have to be integrated, and there may be a gap between the layers.

  The shielding member 58 is provided in the vicinity of the ion extraction unit 22 so as to block the space between the plasma chamber 12 and the insulating mechanism 50. As shown in FIG. 1, the shielding member 58 is a plate-like member that extends radially outward from the side wall portion 20 or the ion extraction portion 22 of the plasma chamber 12, and the thickness direction thereof is the axial direction. It is provided as follows. The shielding member 58 is provided so as to surround the plasma chamber 12 continuously in the circumferential direction. The shielding member 58 is provided so as to form a step with the extraction surface 22a of the ion extraction portion 22. However, in a modified example, the shielding member 58 may be provided so as to form a plane continuous with the extraction surface 22a.

  The shielding member 58 is provided at a position between the first end 50 c of the insulating mechanism 50 and the extraction electrode 40, and the first end 50 c is not seen from the extraction electrode 40. It is provided at a blocking position. The shielding member 58 is provided so as to protrude outward in the radial direction from the position of the inner surface 50 a of the insulating mechanism 50. This protects the insulating member 52 from radiant heat from the extraction electrode 40 that is relatively high during operation of the ion source 10 and prevents the sputtered particles scattered from the extraction electrode 40 from adhering to the insulating member 52. By preventing adhesion of sputtered particles, it is possible to suppress the occurrence of creeping discharge due to the formation of a conductive film on the surface of the first end portion 50c.

  The shielding member 58 is preferably made of a material having excellent conductivity and heat resistance, and is preferably made of a high melting point material such as graphite (C). The shielding member 58 is electrically connected to the plasma chamber 12 and has the same potential as the plasma chamber 12 to which a high voltage is applied. This reduces the electric field generated between the plasma chamber 12 and the insulating member 52 in the vicinity of the ion extraction portion 22. The shielding member 58 does not need to completely close the opening between the plasma chamber 12 and the insulating member 52, and is provided so that there is a gap 60 between the plasma chamber 12 and the insulating member 52. Further, the shielding member 58 is provided with a plurality of vent holes 58a penetrating the shielding member 58. Thus, by providing the vent hole 58a and the gap 60, it is easy to remove air between the plasma chamber 12 and the insulating member 52, and the time required for evacuation of the vacuum vessel 18 is not prolonged.

  Next, the effect produced by the insulation mechanism 50 according to the present embodiment will be described. FIG. 3 is a diagram schematically showing an electric field E and a magnetic field B generated between the plasma chamber 12 and the magnetic field generator 16 in the ion source according to the comparative example. The comparative example is different from the present embodiment in that the insulating mechanism 50 is not provided. As illustrated, an electric field E is generated in the radial direction between the plasma chamber 12 and the magnetic field generator 16 having different potentials, and a magnetic field B generated by the magnetic field generator 16 is generated in an axial direction intersecting the electric field E. . Therefore, the electrons existing in the region between the plasma chamber 12 and the magnetic field generator 16 are accelerated by drifting the electrons by the orthogonal magnetic field B and electric field E.

  Further, since the plasma chamber 12 and the magnetic field generator 16 are provided in a vacuum vessel, a small amount of residual gas exists in the vacuum in the region between the plasma chamber 12 and the magnetic field generator 16. For this reason, the residual gas is ionized by collision of electrons accelerated by drift, and plasma P is generated in a region between the plasma chamber 12 and the magnetic field generator 16. Then, current may flow between the plasma chamber 12 and the magnetic field generator 16 due to the generated plasma P, and insulation may not be ensured. In addition, if a current flows between the plasma chamber 12 and the magnetic field generator 16, the power source 62 that applies the plasma chamber 12 to a high voltage may be affected.

  FIG. 4 is a diagram schematically illustrating an insulating mechanism 150 according to a comparative example. The insulating mechanism 150 is common to the embodiment in that it includes an insulating member 152, an inner conductor layer 154, and an outer conductor layer 156, but a plurality of conductor layers and a plurality of insulating layers are not alternately stacked. This is different from the embodiment. In the comparative example, the inner conductor layer 154 has the same potential as the plasma chamber 12, and the outer conductor layer 156 has the same potential as the magnetic field generator 16, so the potential difference V between the plasma chamber 12 and the magnetic field generator 16 is an insulating member. 152 is applied. As a result, it is possible to prevent a radial electric field from being generated in the space between the plasma chamber 12 and the magnetic field generator 16 and to prevent the continuous generation of plasma in the region between the plasma chamber 12 and the magnetic field generator 16. . Thereby, the discharge between the plasma chamber 12 and the magnetic field generator 16 can be suppressed, and the insulation between them can be enhanced. Specifically, the current value flowing between the plasma chamber 12 and the magnetic field generator 16 can be reduced to about 1/100.

  However, when the insulating mechanism 150 of FIG. 4 is used, all of the high voltage between the plasma chamber 12 and the magnetic field generator 16 is applied to the insulating member 152. Therefore, it is necessary to select a material having a high withstand voltage as the insulating member 152, and the insulating member 152 needs to be thick. For example, in the case where a high pressure-resistant ceramic material such as alumina is used as the insulating member 152, the insulating mechanism 150 becomes heavy if the thickness is increased to increase the pressure resistance. If it does so, it will be necessary to make the fixing structure for attaching the heavy insulation mechanism 150 accurately, and there exists a possibility that the magnitude | size as the whole ion source may enlarge.

  Even if the insulating member 152 is made thick, the insulating property may be destroyed due to temporary local concentration of the electric field, and the insulating member 152 may be cracked 157. In particular, the electric field concentration is likely to occur in the protrusions of the inner conductor layer 154 and the outer conductor layer 156, the triple point structure portion 151 of the insulating mechanism 150, and the like, and there is a high possibility that the discharge phenomenon repeatedly occurs. If the electrical discharge is repeatedly generated in such a place and the insulating property is broken, the crack 157 may develop and the insulating property between the inner conductor layer 154 and the outer conductor layer 156 may not be ensured. If it does so, it will be necessary to replace | exchange the ceramic expensive insulating member 152 frequently, and it may lead to the increase in a maintenance cost.

  FIG. 5 is a diagram schematically illustrating the insulating mechanism 50 according to the embodiment. In the present embodiment, since the insulating member 52 has a plurality of insulating layers 52a and the intermediate conductor layer 55 is provided between the insulating layers 52a, it is possible to prevent the development of cracks as described above. For example, when electric field concentration occurs in the vicinity of the triple point structure portion 51 between the insulating member 52 and the outer conductor layer 56, discharge occurs between the outer conductor layer 56 and the intermediate conductor layer 55 adjacent to the outer conductor layer 56. Is expected. Therefore, the progress of the crack generated in the insulating member 52 can be stopped up to the depth of the intermediate conductor layer 55. Therefore, according to the present embodiment, it is possible to prevent the cracks from penetrating through the insulating member 152 and to prevent the insulating function of the insulating mechanism 50 from being lowered.

  Further, according to the present embodiment, since the intermediate conductor layer 55 extends from the laminated region W1 to the end region W2, the end portions of the inner conductor layer 54 and the intermediate conductor layer 55, that is, the laminated region W1 and The progress of cracks occurring at the boundary of the end region W2 can be suitably prevented. Further, since the end insulators 52c and 52d are provided so as to cover the end portions 55c and 55d of the intermediate conductor layer 55, the occurrence of creeping discharge in the end region W2 can be suppressed, and insulation can be appropriately ensured.

  According to the present embodiment, since the voltage applied to the insulating mechanism 50 is divided by the plurality of insulating layers 52a, a resin material having a lower withstand voltage than ceramic can be used as the insulating member 52. As a result, it is possible to reduce the weight of the insulating mechanism 50, and it is possible to prevent the occurrence of cracks and chips that are likely to occur in ceramic products, so that the insulating mechanism 50 can be handled easily. In addition, by using a resin material having flexibility or flexibility as the insulating member 52, it is possible to improve the processability when manufacturing the cylindrical insulating mechanism 50 corresponding to the plasma chamber 12.

  In addition, according to the present embodiment, since the insulating mechanism 50 is provided between the plasma chamber 12 and the magnetic field generator 16, compared with the case where the insulating mechanism 50 is not used, between the plasma chamber 12 and the magnetic field generator 16. Can be shortened. This is because when the insulating mechanism 50 is not used, it is necessary to earn a distance between the plasma chamber 12 and the magnetic field generator 16 for insulation. According to the present embodiment, since the distance between the plasma chamber 12 and the magnetic field generator 16 can be shortened, the ion source 10 can be further downsized. In addition, since both the plasma chamber 12 and the magnetic field generator 16 are stored inside the vacuum vessel 18, the magnetic field generator 16 can be made smaller than when the magnetic field generator 16 is provided outside the vacuum vessel 18. Can do.

  Moreover, according to this Embodiment, since the magnetic field generator 16 can be made into a grounding potential, it can be attached to the grounded vacuum vessel 18 without using an insulating material. If the magnetic field generator 16 is set to the same high potential as the plasma chamber 12, no electric field is generated between the plasma chamber 12 and the magnetic field generator 16, so that generation of plasma in this region can be suppressed. However, in order to float the magnetic field generator 16 at a high potential, an insulation transformer or the like for connecting the coil power supply of the magnetic field generator 16 is required, which leads to an increase in the size of the ion source 10. In the present embodiment, since the magnetic field generator 16 is at the ground potential, it is not necessary to provide an insulating transformer, and as a result, the ion source 10 can be reduced in size.

(Modification 1)
FIG. 6 is a diagram schematically illustrating a configuration of the insulating mechanism 250 according to the first modification. This modification, the protrusion amount _L a plurality of intermediate conductor layers 255 in the end regions _W2, L b, a difference in _{L c} is provided with the protruding amount of the first intermediate conductive layer 255c located at the center _{L c} Is configured to be maximized. Hereinafter, the insulating mechanism 250 will be described focusing on differences from the above-described embodiment.

  The insulating mechanism 250 includes an insulating member 252, an inner conductor layer 254, a plurality of intermediate conductor layers 255, and an outer conductor layer 256. The plurality of intermediate conductor layers 255 include a first intermediate conductor layer 255c, a second intermediate conductor layer 255a provided between the first intermediate conductor layer 255c and the inner conductor layer 254, a first intermediate conductor layer 255c, and an outer conductor layer. 256 and a third intermediate conductor layer 255b provided between the first and second intermediate conductor layers 256. An insulating layer 252a is provided between the plurality of conductor layers. An end insulator 252c that covers the end of the intermediate conductor layer 255 is provided in the end region W2.

In this modification, the protrusion amount L _c of the first intermediate conductor layer 255c is larger than the protrusion amounts L _a and L _{b of} the second intermediate conductor layer 255a and the third intermediate conductor layer 255b. As a result, the end portions of the plurality of intermediate conductor layers 255 are provided at V-shaped positions where the center is convex. According to the present modification, it is possible to make it difficult to generate a discharge between the conductor layers by shifting the position of the end of the conductor layer where electric field concentration is likely to occur in the axial direction. Further, even when a discharge occurs between the intermediate conductor layers, it is possible to suitably prevent the development of cracks by lengthening the first intermediate conductor layer 255c located at the center in the axial direction.

(Modification 2)
FIG. 7 is a diagram schematically illustrating a configuration of an insulating mechanism 350 according to the second modification. This modified example is different from the above-described embodiment in that the positions of the end portions 354c and 356c of the inner conductor layer 354 and the outer conductor layer 356 are shifted in the axial direction. Hereinafter, the insulating mechanism 350 will be described focusing on differences from the above-described embodiment.

  The insulating mechanism 350 includes an insulating member 352, an inner conductor layer 354, a plurality of intermediate conductor layers 355, and an outer conductor layer 356. As for the inner side conductor layer 354 and the outer side conductor layer 356, the position of each edge part 354c, 356c has shifted | deviated to the axial direction. The plurality of intermediate conductor layers 355 extend in the axial direction so as to protrude from the position on the line segment connecting the end portions 354c and 356c of the inner conductor layer 354 and the outer conductor layer 356 toward the end region W2. . An insulating layer 352a is provided between the plurality of conductor layers. An end insulator 352c that covers the end of the intermediate conductor layer 355 is provided in the end region W2.

  According to this modification, the positions of the inner conductor layer 354 having the triple point structure and the end portions 354c and 356c of the outer conductor layer 356 that are easily concentrated in the electric field are shifted in the axial direction. You can earn. Further, by projecting the position of the intermediate conductor layer 355 toward the end region W2, the end position of the intermediate conductor layer 355 can be shifted in the axial direction from the position of the triple point structure. Thereby, generation | occurrence | production of the discharge between conductor layers can be prevented and the insulation of the insulation mechanism 350 can be improved.

(Modification 3)
FIG. 8 is a diagram schematically illustrating a configuration of an insulating mechanism 450 according to the third modification. This modification is different from the above-described embodiment in that an uneven structure 453 is provided on the end insulator 452c. The concavo-convex structure 453 is provided so as to be concave or convex in the axial direction, and is formed in the circumferential direction along the end of the insulating mechanism 450. According to this modification, by providing the end insulator 452c with the uneven structure 453, the length along the end surface of the insulating member 452 is increased, and creeping discharge between the inner conductor layer 54 and the outer conductor layer 56 is caused. Generation can be suppressed.

  In the above, this invention was demonstrated based on the Example. It is understood by those skilled in the art that the present invention is not limited to the above-described embodiment, and various design changes are possible, and various modifications are possible, and such modifications are within the scope of the present invention. It is a place.

  In the above embodiment, the case where the outer conductor layer 56 is used while being grounded has been described. In the modification, the outer conductor layer 56 may be used so as to have a floating potential without being grounded. That is, the outer conductor layer 56 may be used in a state of being substantially insulated from other members. In this case, the outer conductor layer 56 is charged due to the plasma generated between the magnetic field generator 16 and the outer conductor layer 56, and a counter electric field that reduces the electric field between the magnetic field generator 16 and the outer conductor layer 56 is generated. . By utilizing this counter electric field, the electric field between the magnetic field generator 16 and the outer conductor layer 56 can be reduced to suppress the generation of plasma.

  In the above-described embodiment, the case where the intermediate conductor layer 55 has three layers and the insulating layer 52a has four layers has been described. In the modification, the intermediate conductor layer 55 may be one layer or two layers, or may be four layers or more. In this case, the number of insulating layers 52 a corresponding to the number of intermediate conductor layers 55 may be provided. In addition, each conductor layer and each insulating layer may be configured with a single layer structure, or may be configured with a multilayer structure of a plurality of layers. For example, each insulating layer may be composed of a multilayer body or a laminated body in which a plurality of insulating sheets are laminated.

  In the above-described embodiment, the case where the insulating mechanism 50 is used as the insulating structure of the ion source has been described. In a modification, it may be used as an insulating structure in a device having a different purpose, or may be used to electrically insulate between an arbitrary first member and a second member. In this case, the insulating mechanism includes a laminated region in which a plurality of conductor layers and a plurality of insulating layers are alternately laminated in a direction from the first member to the second member, and end insulation that covers end portions of the plurality of conductor layers. And an end region where the body is provided. The insulating layer and the end insulator may be made of a resin material such as polyimide.

  DESCRIPTION OF SYMBOLS 10 ... Ion source, 12 ... Plasma chamber, 16 ... Magnetic field generator, 18 ... Vacuum container, 50 ... Insulation mechanism, 50a ... Inner side surface, 50b ... Outer side surface, 52a ... Insulating layer, 54 ... Inner conductor layer, 55 ... Middle Conductor layer, 56 ... outer conductor layer, W1 ... laminated region, W2 ... end region.

Claims (8)

A plasma chamber to which a high potential is applied;
An insulating mechanism provided so as to surround the outer periphery of the plasma chamber;
A magnetic field generator provided outside the insulating mechanism and generating a magnetic field in the plasma chamber;
A vacuum vessel that houses the plasma chamber, the insulation mechanism, and the magnetic field generator;
With
The ion source has a plurality of conductor layers and a plurality of insulating layers alternately stacked in a direction from the plasma chamber toward the magnetic field generator.   The plurality of conductor layers are located between an inner conductor layer constituting an inner surface of the insulation mechanism, an outer conductor layer constituting an outer surface of the insulation mechanism, and between the inner conductor layer and the outer conductor layer. The ion source according to claim 1, comprising the above intermediate conductor layer.   The ion source according to claim 2, wherein at least one of the inner conductor layer and the outer conductor layer is provided to avoid an end region of the insulating mechanism.   The ion source according to claim 3, wherein the insulating mechanism includes an end insulator that covers an end of the one or more intermediate conductor layers in the end region.   5. The ion source according to claim 4, wherein the one or more intermediate conductor layers protrude from the laminated region where the inner conductor layer and the outer conductor layer are laminated toward the end region. The one or more intermediate conductor layers include a first intermediate conductor layer, a second intermediate conductor layer provided between the first intermediate conductor layer and the inner conductor layer, the first intermediate conductor layer, and the outer conductor layer. A third intermediate conductor layer provided between
6. The ion source according to claim 5, wherein the first intermediate conductor layer has a larger protruding amount that protrudes toward the end region than the second intermediate conductor layer and the third intermediate conductor layer.   The ion source according to claim 4, wherein the end insulator has an uneven structure.   An insulating mechanism for electrically insulating between a first member and a second member, wherein a plurality of conductor layers and a plurality of insulating layers are alternately stacked in a direction from the first member toward the second member An insulating mechanism comprising: a region; and an end region provided with an end insulator covering the ends of the plurality of conductor layers.

Images